It is known in the prior art to apply artificial nails to the surface of natural human fingernails. One method used is to attach an artificial preformed fingernail or portion of a fingernail to the natural nail by means of an adhesive. After these artificial nails are attached to the natural nail they must be filed at their lower terminal surface portion to blend with the natural nail. The result is, in many cases, not natural appearing since quite often the junction of the artificial nails tends to bend, become separated or become distorted when worn and must be removed or replaced. A typical artificial nail of this type is disclosed in U.S. Pat. No. 2,941,535. The adhesive disclosed in this prior art patent comprises a polymerizable acrylic ester monomer such as alkymethacrylate which has a filler formulated therewith. An additional drawback to this type nail is that the nail must be provided with holes to permit the adhesive to bond properly to the natural nail. Other preformed nails, molds, coatings or film formed nails are disclosed in U.S. Pat. Nos. 3,037,514; 3,157,912; 3,425,426 and 3,483,289.
Some prior art patents deal with mending broken fingernails and others with the use of substances applied to the nail surface to strengthen the natural nail. In most of these compositions, the hardenable substance is applied directly to the surface of nails and allowed to dry and harden. A large portion of these prior art compositions contain lower alkymethacrylate monomers and polymers. Usually these compositions are formulated from a powder mix and a compatible liquid. The liquid generally contains a polymerization accelerator and the powder a polymerization initiator. The powder when mixed is allowed to substantially dissolve in the liquid and when the methacrylate polymerizes the material cures and hardens. Many components are incorporated into these prior art compositions such as colorants, color stability agents and others. Typical coatings for nails are disclosed in U.S. Pat. Nos. 4,104,333; 4,229,431; 4,260,701 and 4,495,172.
In U.S. Pat. No. 4,104,333 a self-curing artificial nail composition is disclosed which contains a cross-linkable monomer such as ethylene glycol dimethacrylate, a furfuryl methacrylate, benzoyl peroxide, a tertiary amine-type accelerator, a polymeric filler and a flexibilizing material. The set time for the compositions of this prior art invention, usually about 120 to 400 seconds, may be regulated by varying the concentration of initiators and/or accelerators. Inorganic fillers such as finely divided alumina silicates, silica, quartz, glass and the like may be used to control consistency of material and improve its physical mechanical properties.
Generally, as suggested hereinbefore, a polymeric filler material which may be soluble, partially soluble, or insoluble in the resin matrix is present. Typically, but not necessarily, these polymers or copolymers of the monomeric materials are used in the in-situ polymerization composition. Suitable in prior art compositions and for the compositions of the present invention are copolymers of ethyl and methylmethacrylate, polyethylmethacrylate, polymethyl methacrylate, polymethyl acrylate, polyethyl acrylate and polypropyl acrylate. In other words, polymers of the monacrylates herein contemplated are suitable. The above-mentioned fillers are usually present in a concentration of less than about 40%, preferably from about 5% to about 55% by weight. Minor conventional amounts of modifiers may also be present such as dyes, opaquing agents (e.g. titanium dioxide), and stabilizers (e.g. 3-butyl-4-hydroxytoluene).
In U.S. Pat. No. 4,229,431 a method of forming a coating for a human nail is disclosed and claimed. In this prior art patent a flowable material containing methacrylate monomers and polymers is applied to the nail and allowed to harden in-situ on the nail. It is then formed to the desired shape by filing and the like. The composition used in this prior art patent is a two component powder-liquid formulation having the following typical make-up:
______________________________________ Percent by Weight ______________________________________ Part A (Powder) 70/30 copolymer of ethyl and methyl 99.1 methacrylate benzoyl peroxide (catalyst) 0.8 titanium dioxide (opaquing agent) 0.1 Part B (Liquid) methyl methacrylate 78.35 polyethylene glycol dimethacrylate 20.0 dimethyl-p-toluidine (accelerator) 1.0 2-hydroxy-4-methoxy benzophenone 0.5 (UV-absorber) 3-butyl-4-hydroxy toluene (stabilizer) 0.05 dye 0.1 ______________________________________
In this patent, both parts (be they liquid/powder or paste/paste) are applied separately and mixed directly on the nail. Alternatively, both parts may be pre-mixed immediately before application on the nail or substrate elongator.
In U.S. Pat. No. 4,260,701 a fingernail coating composition having an acrylic binder, a peroxide catalyst, a tertiary amine accelerator and a polymeric filled soluble in the coating is disclosed. The acrylic binder contains a mono-ethylenically unsaturated monomer comprising at least a major proportion of methoxyethyl methacrylate.
In U.S. Pat. No. 4,495,172 a coating composition is disclosed. The coating composition comprises a curable ethoxyethylmethacrylate monomer, a polyethylmethacrylate homopolymer or copolymer filler and a cross-linking agent. The method involves applying the coating composition upon nails and curing the composition. The product involves a separately packaged liquid and powder, wherein the liquid comprises ethoxyethylmethacrylate monomer and a cross-linking agent and the powder comprises a polyethylmethacrylate and filler.
While the compositions disclosed in 4,495,172; 4,260,701; 4,229,431 and 4,104,333 are appropriate for forming curable artificial nail compositions, they also possess certain inherent drawbacks. In some instances the nail composition dries to a surface that does not have the appropriate color or texture of a natural nail. Some of these prior art compositions easily separate from the human nail when dried or worn. In other instances the broken or damaged nail being covered does not heal or grow strong while being covered by the artificial nail. In other instances a fungus or other infection occurs in the space between the natural and artificial nail. Also, prior art artificial nails have a tendency to crack easily and are required to be worn for long periods of time before the natural nail is repaired and healed.